Free access article

Issue A&A Volume 388, Number 2, June III 2002 Page(s) L33 - L36 Section Letters DOI 10.1051/0004-6361:20020569

A&A 388, L33-L36 (2002)
DOI: 10.1051/0004-6361:20020569

Letter

Evidence for synchrotron bubbles from GRS 1915+105

C. H. Ishwara-Chandra¹, J. S. Yadav² and A. Pramesh Rao<sup>3

1</sup>  Space Astronomy and Instrumentation Division, ISRO Satellite Center, Bangalore 560 017, India
²  Tata Institute of Fundamental Research, Homi Bhaba Road, Mumbai 400 005, India
³  National Center for Radio Astrophysics, Post Bag No. 3, Ganeshkhind, Pune 411 007, India

(Received 18 February 2002 / Accepted 12 April 2002)

Abstract
We present GMRT observations of the Galactic microquasar GRS 1915+105 at 1.28 GHz for 8 days from 2001 June 18 to July 1. We have seen several isolated radio flares of varying magnitudes (20-50 mJy) and durations (6-35 min) and we model them as due to adiabatically expanding synchrotron emitting clouds (synchrotron bubbles) ejected from the accretion disk. By applying this model, we provide a new method to estimate the electron power-law index p, hence the spectral index, from single frequency radio observations. This method does not require correction for the optical time delay effects which may be important in the case of optically thick radio emission. Using our estimated value of p and simultaneous multiwavelength data from literature, we have calculated the time of ejection of the synchrotron plasma and the time delays at different observed frequencies. Our estimates are in good agreement with the observed time delays.

Key words: stars: individual: GRS 1915+105 -- radio continuum: stars -- X-rays: binaries

Offprint request: C. H. Ishwara-Chandra, ishwar@ncra.tifr.res.in

SIMBAD Objects

© ESO 2002

What is OpenURL?